1. Field of the Invention
The present invention relates to a linearly moving mechanism for reciprocally moving articles along a straight line, and particularly to a linearly moving mechanism suitable for use in, for example, a semiconductor device transporting and handling (processing) apparatus (commonly called handler) for transporting semiconductor devices such as semiconductor integrated circuit elements for testing purposes and sorting out the tested semiconductor devices on the basis of the test results.
2. Description of the Related Art
First, a semiconductor device transporting and handling apparatus (which will be referred to as handler hereinafter) which is typical of the apparatus utilizing the linearly moving mechanism of the type concerned will be described. FIG. 4 illustrates the general construction of one example of the conventional IC handler called "horizontal transporting system". This handler is designed to be used in conjunction with a semiconductor device testing apparatus for testing semiconductor devices, particularly an IC testing apparatus (commonly called IC tester) for testing semiconductor integrated circuit elements (which will be referred to as IC hereinafter) typical of semiconductor devices, so that articles moved by the linearly moving mechanism are ICs. It is to be understood, however, that the linearly moving mechanism of the type disclosed herein may also be used with any apparatus for linearly moving articles other than ICs.
The illustrated handler includes a plurality of tray groups 2A-2E arranged along the lower side as viewed in the drawing of the platform 1 constituting a base. Each of the tray groups 2A-2E comprises a plurality of trays stacked vertically one on another (the tray group 2E contains only one tray in the illustrated example). The leftmost tray group 2A in the drawing is located in the loader section. Each of the trays of the tray group 2A in the loader section is loaded with a plurality of ICs to be tested (ICs under test).
X-Y carrier arms 3A, 3B pick up two, in this example, ICs under test at a time from the uppermost tray of the tray group 2A positioned at the loader section, and transport them onto a rotary IC transport 4 (which is also termed turntable) called "soak stage". Two, in this example, rows of positioning recesses 5 for defining the positions for receiving the ICs are formed in the IC transport 4 at equal angular intervals on concentric circles. Each positioning recess 5 is of substantially square shape and is surrounded on four sides by upwardly inclined walls. Each time the IC transport 4 rotates by one pitch, the X-Y carrier arms 3A, 3B drops two ICs down into corresponding ones of the two concentric rows of positioning recesses 5. More specifically, attached to the Y carrier arm, in this example, of the X-Y carrier arms 3A, 3B is a transport head 3C which is adapted to pick up two ICs under test from the uppermost tray of the tray group 2A at the loader section and transport the thus grasped ICs onto the IC transport 4 by virtue of the movements in the X-Y directions of the X-Y carrier arms 3A, 3B.
The ICs conveyed by the IC transport 4 are delivered into the test section 7 by a rotary type transfer arm 6 referred to as contact arm. Specifically, the contact arm 6 is adapted to pick up two ICs, one from each of the positioning recesses 5 in the IC transport 4 and transport them to the test section 7. The contact arm 6 has three arms each provided with a transport head, and performs the operations, by rotation of the three arms, of successively delivering the ICs under test to the test section 7 and of successively transferring the ICs tested in the test section 7 to a rotary type transfer arm 8 on the exit side.
It should be noted that the IC transport 4, the contact arm 6 and the test section 7 are contained in a constant temperature chamber 9 (usually referred to as chamber) so that ICs may undergo the testing within the chamber 9 while being maintained at a predetermined temperature. In this regard, the arrangement is such that the temperature in the interior of the constant temperature chamber 9 may be controlled to either a designed high temperature (such as 125.degree. C.) or low temperature (such as -55.degree. C.) so that the ICs to be tested may be applied with a predetermined temperature stress. It should be noted that the rotary transfer arm 8 on the exit side is so configured that one of its arms is normally positioned in the interior of the constant temperature chamber 9.
The rotary transfer arm 8 on the exit side has also three arms each provided with a transport head, and delivers, by rotation of the three arms, the tested ICs grasped by the transport heads out to the unloader section. The tested ICs taken out of the constant temperature chamber 9 are sorted out on the basis of the test results and stored in corresponding one of the three, in this example, tray groups 2C, 2D and 2E located in the unloader section. By way of example, non-conforming or defective (failure) ICs are stored in a tray of the rightmost tray group 2E, conforming or defectless (pass) ICs are stored in a tray of the tray group 2D to the left of the group 2E, and ICs requiring re-testing are stored in a tray of the tray group 2C further to the left of the group 2E. This sorting is controlled on the basis of the data of the test results and operated by the X-Y carrier arms 10A, 10B. The Y carrier arm 10A, in this example, is equipped with a transport head 10C which is adapted to pick up ICs tested and sorted out and deliver to an appropriate tray.
It is to be noted that the trays of the second leftmost tray group 2B as viewed in the drawing are empty ones located at the empty tray buffer stage for accommodating trays emptied of ICs in the loader section. When the uppermost one of the stacked trays of any of the tray groups 2C, 2D and 2E is filled with ICs, a tray of the empty tray group 2B is conveyed to the top of the filled tray to be used to store ICs therein.
The contact arm 6 mentioned above will be described in more details with reference to FIGS. 5 and 6. The contact arm 6 includes a rotary shaft 6A (see FIG. 6) rotatably mounted in the thermally insulating top wall 11 of the constant temperature chamber 9 and having an arm supporting block 6B secured to the lower end thereof. Three arms 18 (only one of which is visible in FIG. 5) extend generally horizontally and radially from the arm supporting block 6B at angular intervals of about 120.degree.. Each of the arms 18 is an L-shaped member having a generally horizontally extending main arm portion 18A and a vertical leg portion 18B depending at a substantially right angle from the main arm portion 18A and the three arms 18 are caused to rotate by rotation of the rotary shaft 6A.
Each arm 18 has a linear guide rail 31 extending vertically along the length of and attached to the outer wall of the depending leg portion 18B, and a pair of movable members 32 are engaged with the linear guide rail 31 for sliding movement vertically therealong. The movable members 32 are secured to the vertical wall of a head supporting member 14 adjacent its upper end which comprises a plate-like member having opposite ends bent at generally right angles and reinforced with a reinforcement member 14A. Mounted to the lower end or free end of the head supporting member 14 is a transport head 13 for grasping and angularly transporting ICs. It will thus be appreciated that the head supporting member 14 and the transport head 13 are mounted by means of the movable members 32 and the linear guide rail 31 for vertical motions relative to the depending leg portion 18B of the associated arm 18. The transport head 13 is provided with two, in this example, vacuum pick-up heads adapted to vacuum attract and grasp ICs for angular conveyance.
In addition, a tension coil spring 19 extends vertically and are connected at opposite ends with an arm member 15 affixed to each IC supporting member 14 adjacent its lower end and an arm member 20 affixed to the depending leg portion 18B of the associated arm 18 adjacent its upper end so that each IC supporting member 14 is normally upwardly biased by the tension of the tension coil spring 19 to be kept stationary at a predetermined position (shown in FIG. 6) along the outer wall of the depending leg portion 18B of the associated arm 18.
The rotary IC transport (soak stage) 4 includes a rotary shaft (not shown) rotatably mounted in the thermally insulating bottom wall 12 of the constant temperature chamber 9 and is spaced a predetermined distance above the bottom wall 12. The rotary IC transport 4 is constructed of a hub portion and a peripheral portion interconnected by six spokes in this example. ICs to be tested are placed for transportation in two, in this example, concentric rows of positioning recesses 5 formed in the peripheral portion.
In the conventional handler illustrated in FIGS. 4-6, since the test section 7 is located vertically below the rotary IC transport 4, a cam 24 in the form of a semi-annular ring in plan view having a generally inverted triangular peripheral surface (see FIG. 5) is mounted on the handler concentrically with the rotary shaft of the contact arm 6 such that the IC supporting member 14 is caused to descend to position the transport head 13 at an elevation of a predetermined distance above the test section as ICs are picked up and angularly moved by the transport head 13. It is to be appreciated by those skilled in the art, however, that this is only one example and that the present invention is not limited to the application to the configuration and construction of the handler as illustrated herein, since some linearly moving mechanism is required even if the test section 7 is in the same plane as the IC transport 4.
Although the cam 24 is fixed and will not itself move to drive a cam follower, it is called "cam" in this disclosure because it performs virtually the same function as the cam.
With the construction as described above, when one of the arms 18 of the contact arm 6 is rotated and comes to a standstill at a predetermined position over the IC transport 4 as shown in FIG. 6, the other two arms 18 come to a stop at a predetermined position over the test section 7 and at the point of transfer (buffer stage) to the rotary transfer arm 8 on the exit side, respectively. At these stop positions, push rods 21 are disposed at predetermined angular intervals in overlying and opposed relation to the associated IC supporting members 14, respectively. Each push rod 21 is vertically movably mounted in the top wall 11 of the constant temperature chamber 9 such that the push rod 21 may be lowered through a predetermined stroke by a drive means, not shown upon the three arms 18 of the contact arm 6 arriving at the predetermined positions over the IC transport 4, the test section 7, and the buffer stage, respectively.
The operation of one of the arms 18 which has stopped at a position over the IC transport 4 will now be described specifically with reference to FIG. 6. As the associated push rod 21 is lowered through a predetermined stroke by the drive source, the lower end 21A of the push rod 21 comes into abutment against the top of the IC supporting member 14 before pushing down on the IC supporting member 14 whereby the pair of movable members 32 attached to the IC supporting member 14 are moved downwardly slidingly along the linear guide rail 31 affixed to the depending leg portion 18B of the arm 18 against the tensioning force of the coil spring 19 while the IC supporting member 14 in unison with the transport head 13 is depressed. As the push rod 21 is lowered by a predetermined distance, the vacuum heads of the transport head 13 are lowered by a predetermined distance of travel (stroke) ST whereupon the vacuum heads of the transport head 13 come into contact with the ICs under test placed in the positioning recesses 5 of the IC transport 4. Otherwise stated, the downward stroke of the push rod 21 lowered by the drive means is defined so as to be equal to the distance through which the vacuum heads of the transport head 13 are moved from its predetermined stop position down to the position where they come into contact with the ICs under test placed in the positioning recesses 5 of the IC transport 4.
Upon the vacuum heads of the transport head 13 picking up and holding the ICs under test, the drive source is deactivated. As a result, the IC supporting member 14 is pulled upwardly by the tensioning force of the coil spring 19 with the pair of movable members 32 sliding upwardly along the linear guide rail 31 until the IC supporting member 14 arrives at its original stop position where it is stopped. It is thus to be understood that two ICs 16 under test vacuum attracted against the transport head 13 are moved from the positioning recesses 5 of the IC transport 4 up to the upper predetermined position.
With regard to the test section 7, as the associated push rod 21 is lowered through a predetermined stroke by the drive source, ICs under test attracted against the transport head 13 are caused by the same moving operation as described above to move from their predetermined stop position down to the position where they come into contact with the sockets, not shown in the test section 7. In this state, the ICs under test undergo the test. Upon the test being completed, the drive source for the push rod 21 is deactivated. As a result, the IC supporting member 14 is pulled upwardly by the tensioning force of the coil spring 19 until the IC supporting member 14 arrives at its original stop position where it is stopped. The two tested ICs remain vacuum attracted against the transport head 13.
Similarly, in the buffer stage where the ICs are transferred to the rotary transfer arm 8 on the exit side, as the associated push rod 21 is lowered through a predetermined stroke by the drive source, the tested ICs attracted against the transport head 13 are caused by the same moving operation as described above to move from their predetermined stop position down onto the buffer stage. In this state, the vacuum suction force of the transport head 13 is terminated to release the tested ICs from the transport head 13, followed by the drive source for the push rod 21 is deactivated. As a result, the IC supporting member 14 is pulled upwardly by the tensioning force of the coil spring 19 until the IC supporting member 14 arrives at its original stop position where it is stopped. No ICs are now present on the transport head 13 while the two tested ICs are placed on the buffer stage at a predetermined position.
It is thus to be appreciated that the rotary transfer arm 8 on the exit side may also use a linearly moving mechanism similar to that described above to transport tested ICs from the buffer stage to the unloader section.
As discussed above, since the prior art linearly moving mechanism comprises the linear guide rail 31 of the depending leg portion 18B of each arm 18 of the contact arm 6 and the pair of movable members 32 secured to the head supporting member 14, it is seen in FIG. 6 that the effective length L of the linear guide rail 31 actually required for allowing the movable members 32 to slide therealong is equal to the sum of the actually required stroke ST of the transport head 13 and at least the length P of the movable members 32 (L=ST+P).
In order to insure stable and reliable sliding motions of the movable members 32 as well as to allow for the adjustment of the stroke of the movable members 32, it is to be appreciated from FIG. 6 that the linear guide rail 31 actually extends upwardly and downwardly beyond the stop positions (the uppermost and lowermost positions) of the movable members 32. Consequently, the actual length of the linear guide rail 31 is often made about twice as long as the effective length L thereof.
Accordingly, it has heretofore been required that the distance or spacing between the top wall 11 and the bottom wall 12 of the constant temperature chamber 9 be made at least a little over twice as long as the effective length L of the linear guide rail 31, resulting in the sincere disadvantage that the oversized constant temperature chamber 9 leads necessarily to oversizing of the entire handler.
The aforesaid disadvantage is not limited to the handler as described above, but may be the case with any other handler called horizontal transporting system if the linearly moving mechanism of the type described above is used in the constant temperature chamber 9.
By way of example, the handler of the type illustrated in FIG. 7 is often employed which comprises a loader section 44 where ICs 42 to be tested which have been beforehand loaded on a customer tray (user tray) 41 by a user are transferred and reloaded onto a test tray 43 capable of withstanding high/low temperatures; a constant temperature chamber 47 including a soak chamber 45 for applying a predetermined temperature stress to the ICs 42 under test transported from the loader section 44 and a test section 46 for receiving and testing the ICs 42 under test to which a predetermined temperature stress has been applied; and an unloader section 49 where the tested ICs which have been carried on the test tray 43 from the test section 46 to an exit chamber 48 and which have been delivered out of the exit chamber 48 subsequently to being relieved of a temperature stress are transferred from the test tray 43 to the customer tray 41 to be reloaded on the latter (generally, the tested ICs are often sorted out by categories based on the data of the test results and transferred onto the corresponding customer trays.). The test tray 43 is moved in a circulating manner from and back to the loader section 44 sequentially through the constant temperature chamber 47 and the unloader section 49. In the test section 46, the ICs 42 under test are brought into electrical contact with IC sockets to be subjected to the test.
This type of handler may also require X-Y transport apparatus and linearly moving mechanism, if the handler is configured to pick up ICs under test from the test tray 43 and transfer them onto the IC sockets in the test section 46 to test them. It will thus be appreciated that as is the case with the handler illustrated in FIGS. 4-6, the handler described just above may also be attended with the sincere disadvantage that the actual length of the linear guide rail of the linearly moving mechanism is made a little over twice as long as the effective length thereof, requiring that the constant temperature chamber 47 and hence the entire handler be oversized.
Not only in the handler but also in any other apparatus in which it is required to use the linearly moving mechanism constructed as described above within a space (chamber) bounded by a top wall (ceiling) and a bottom wall (floor), the actual length of the linear guide rail of the linearly moving mechanism is made a little over twice as long as the effective length thereof, so that the spacing between the top wall and the bottom wall of the space accommodating the linearly moving mechanism is undesirably increased, resulting in oversizing the entire apparatus.